IQueryable Interface (System.Linq)

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Microsoft Visual Studio 2010/.NET Framework 4

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.NET Framework Class Library

IQueryable Interface

Provides functionality to evaluate queries against a specific data source wherein the type of the data is not specified.

Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)

Syntax

Visual Basic

Public Interface IQueryable _
    Inherits IEnumerable

public interface IQueryable : IEnumerable

Visual C++

public interface class IQueryable : IEnumerable

type IQueryable =  
    interface
        interface IEnumerable
    end

The IQueryable type exposes the following members.

Properties

	Name	Description
	ElementType	Gets the type of the element(s) that are returned when the expression tree associated with this instance of IQueryable is executed.
	Expression	Gets the expression tree that is associated with the instance of IQueryable.
	Provider	Gets the query provider that is associated with this data source.

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Methods

	Name	Description
	GetEnumerator	Returns an enumerator that iterates through a collection. (Inherited from IEnumerable.)

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Extension Methods

	Name	Description
	AsParallel	Enables parallelization of a query. (Defined by ParallelEnumerable.)
	AsQueryable	Converts an IEnumerable to an IQueryable. (Defined by Queryable.)
	Cast<(Of <(TResult>)>)()()()	Overloaded. Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
	Cast<(Of <(TResult>)>)()()()	Overloaded. Converts the elements of an IQueryable to the specified type. (Defined by Queryable.)
	OfType<(Of <(TResult>)>)()()()	Overloaded. Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
	OfType<(Of <(TResult>)>)()()()	Overloaded. Filters the elements of an IQueryable based on a specified type. (Defined by Queryable.)

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Remarks

The IQueryable interface is intended for implementation by query providers. It is only supposed to be implemented by providers that also implement IQueryable<(Of <(T>)>). If the provider does not also implement IQueryable<(Of <(T>)>), the standard query operators cannot be used on the provider's data source.

The IQueryable interface inherits the IEnumerable interface so that if it represents a query, the results of that query can be enumerated. Enumeration causes the expression tree associated with an IQueryable object to be executed. The definition of "executing an expression tree" is specific to a query provider. For example, it may involve translating the expression tree to an appropriate query language for the underlying data source. Queries that do not return enumerable results are executed when the Execute method is called.

For more information about how to create your own LINQ provider, see LINQ: Building an IQueryable Provider on MSDN Blogs.

Version Information

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

System.Linq Namespace

Queryable

IQueryable<(Of <(T>)>)